It is known that the blades of a rotary wing rotor are controlled in a collective pitch and in a cyclic pitch.
The collective pitch allows for the stationary flight of the helicopter through a positioning being identical in incidence to all the blades with respect to the rotation axis of said rotor, then confused with the driving axis for the pylon thereof, said collective pitch generating a general lift being aligned with the vertical and balancing the bulk of the helicopter.
As far as it is concerned, the cyclic pitch allows, through a positioning in incidence for each blade as a function of the azimuth, to tilt the general lift with respect to the vertical and thus to move said helicopter.
For the collective pitch and the cyclic pitch control, rotors generally comprise a mechanism, referred to as a cyclic plate, mounted on the pylon of the rotor and comprising a rotary plate connected to each blade by a pitch control rod and driven in rotation by rotating scissors, a stationary plate sliding along the pylon of the rotor and able to be tilted with respect to the latter and a bearing link between said stationary and rotary plates.
Such a cyclic plate is disadvantageous in that it comprises a large number of mechanical parts requiring it to be regularly maintained and checked.
It has therefore already been contemplated to remove said cyclic plate while mounting mobile flaps on said blades, the cyclic pitch thereof being controlled by the twist of said blades generated by the torsion moment induced by the extension of said flaps and the collective pitch of the blades being obtained either similarly to that of the propellers, or by an actuator arranged at the blade shank.
However, such mobile flaps also require using sophisticated and friction-sensitive mechanical assemblies.